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Ongoing complex of thunderstorms pushing into south central MN this hour. Have a new set of thunderstorms forming in what AllSky is showing as a higher CAPE environment along the outflow pushing out from this complex. ProbSevere has picked up on this cell as well (near Milan)…showing a Hail chance of 55% now and growing quickly. Will monitor the downstream growth of both systems.
Today’s operations will be begin with their focus over the Twin Cities/Chanhassen (MPX) county warning area. Severe storms have already developed and are approaching the Twin Cities area from the northwest. The Storm Prediction Center current has a mesoscale discussion out for the area highlighting potential watch issuance within the next few hours with the main threat being damaging winds but large hail is also possible.
Other potential regions of operation include the low-country region of South Carolina, where there is currently a severe thunderstorm watch, and extreme west Texas into southern New Mexico. We’ll monitor the weather situations in these locations and adjust our operations area as needed.
AzShear has come up a little on a broad scale with that northern cell.
Reflectivity coming down on the south side of that broad circulation…possibly indicating a rear inflow jet pushing into the system.
Charley
AzShear not as high with this cell earlier. Has a similar reflectivity nub to maximize that 0-3 km shear from the southwest. Will have to watch that area.
Charley
We’re comparing AzShear to velocity, SRM, and reflectivity data. I started off focusing on the cell with the longest touchdown near the Mississippi Alabama border. If I was forecasting this event real time the AzShear would help to increase my confidence in length of the period the tornado was on the ground. That’s due to the comparison between the AzShear and SRM.
The rotation signature on the SRM alone appears to weaken as the cell gets closer to Alabama.
Meanwhile, the AzShear holds onto a stronger signature longer aligning more with the actual touchdown. In that case it’s more helpful. 
The only difficulty for me is reprogramming my brain to not look at AzShear the same way I look at velocity. I’m accustomed to finding the couplet, and it’s tempting to do the same with the AzShear product.
AzShear was also helpful in analyzing the southernmost cell that was also showing rotation. Since it was farther from the radar site my confidence in a possible tornado was increased due to the max in the AzShear.
It stands out more in comparison to the velocity data. The cell doesn’t have your typical look of a supercell so reflectivity wasn’t as helpful.
Taylor Johnson
Right in the middle of the reflectivity curl is a gate to gate circulation…also a peak in AzShear.
TDS showed up too.
Charley
Southern discrete cell has a BWER on the 0.5 degree tilt. AzShear way up to 0.018…cannot believe a stronger/longer-tracked tornado wasn’t found with this cell.
Front end nub showing on QLCS…with 700 mb winds from the southwest…that part of the line is going perpendicular to the 0-3 km shear (~45 knots). AzShear has persistently shown a high value for that part of this track as well (.009).
Charley
At first exposure the single radar AzShear product appears to highlight mesoscale regions of interest. Looking at the 2/23/19 ern MS/wrn AL case beginning around 2308z there is a broad area of reflectivity with some evidence of an embedded supercell in east-central MS. The AzShear product shows a linear region of positive values with enhanced values around the potential circulation. Advancing to 2312z the linear AzShear feature has now taken on an S-shape, with enhanced values immediately northern portion of the S. At this time there is a broad low-level circulation.
By 2316z, there is now a break in the ‘S’ in the AzShear, and at this time the low-level circulation is tightening as a supercell is apparent in the reflectivity.
About two minutes later the low-level 0.5 degree circulation is now gate-to-gate. AzShear values are high at the circulation, but also highlight shear along the interface of the FFD and the inflow, as well as along the RFD region.
This same general pattern would continue for the next several minutes. However, by 2324z the trailing RFD or mesoscale cold front pushes ahead of the main circulation and merges with the FFD/inflow interface as the storm appears to mature and the main circulation becomes occluded.
After this time the main circulation fades and the convective organization appears to either transition or recycle. In summary, the single radar AzShear product appears to highlight other regions of interest where shear is present outside the main circulation. These features are important in tornado development and supercell life-cycle, but are not always apparent in reflectivity or in velocity. Of note, the detail in the single radar product has a tendency to become lost or muted in the merged product.
One challenge would be color scales for different portions of the country. Would a color scale for the southern plains be sufficient for the mid-Atlantic, or would smaller weaker features be less noticeable?
The single-radar AzShear product is quite useful in grabbing my attention to areas of high shear that could indicate the presence of tornado or higher level rotation. While not the best in indicating the location of the tornado (Velocity provides more precision), the AzShear helps identify those areas within the storm cell with strong shear, see Fig 1 below.
Figure 1: Single radar AzShear on left, Reflectivity top right, Velocity bottom right. The cursor indicates the center of the tornado based on Vel, but is more in the center of the highest shear on the AzShear product. 
Other ‘hotspots’–whites/light blues in the AzShear product may send forecasters on wild-goose chases, looking for tornadoes, but having velocity data on hand quickly helps toss out the non-tornadic areas.
The MergedAzShear (MAS) product is useful in a broader sense of scale, but probably not as useful as the single radar AzShear. An MAS couplet often becomes distorted with the blending of multiple radar cuts from different radars. Sometimes a single couplet could show 1 or 2 echoes that will resolve into 1 couplet after another scan. For short-fused monitoring of a tornadic storm cell, its position could be misleading. Higher-level MAS, while useful in a broader storm environment seems less likely to depict a tornado, although it will indicate a broader area of high shear and changes in the wind fields. (See Fig. 2).
Figure 2: MergedAzShear (MAS) 3-6km AGL on left, Reflectivity on top right, Velocity on bottom right. The computer cursor is placed near the center of the Velocity-indicated tornado center.
Ultimately, the AzShear is a good tool to use along with Velocity data to get an overview of what is going on within the atmospheric layer (0-2km or 3-6km), even when there is no tornado on the ground, but should be used in tandem with other radar data to help weed out false signals that may be due to ground clutter, etc.
